Framework for developing and using mock objects

* A methodology for developing and using mock objects.
* A core mock object framework. This is a library of code that
supports the implementation of mock objects, based around a
set of expectation classes for values and collections. There are
also various other classes to make mock objects easier to write
or to use.
* A default set of mock implementations for the standard Java
platform APIs. We have made a start on packages such as servlets, sql,
and io.